Known in the art is a digital device for automatically checking the carbon content in metal with reference to temperature arrests on the cooling curve (cf. UK Pat. No. 1,477,564), which comprises an analog-to-digital converter to whose input there is applied a signal carrying information on the actual temperature of the melt. The device also includes a clock pulse generator. Outputs of the analog-to-digital converter are connected, via a synchronization unit for distributing code and clock pulses in time, to add and subtract inputs of a reversible counter, and to inputs of a local temperature increments discriminator. The reversible counter is intended for generating a parallel code of the actual temperature. The local temperature increments discriminator is adjusted so that a pulse is formed at one of its outputs each time a certain positive or negative value .epsilon..sub.o is set therein. An output of the clock pulse generator is connected via the synchronization unit to a count input of a time interval discriminator intended for selecting time intervals during which there occur predetermined temperature increments .+-..epsilon..sub.o. Reset inputs of the time interval discriminator are connected to outputs of the local temperature increments discriminator. The time interval discriminator is constructed so that at its output there is formed a signal only when the selected time interval exceeds a predetermined threshold .tau..sub.o. The output of the time interval discriminator is connected to a control input of a register and a set intput of a flip-flop. The register is connected with its information input to an information output of the reversible counter, and via a functional code converter to an information input of a digital display unit whose control input is connected to a set output of the flip-flop. The functional code converter is designed for converting a parallel code of the liquidus temperature T.sub.1 to a parallel code of carbon content C in the melt, which is found as follows: EQU C=f(T.sub.1), (1)
where f is a general non-linear operator.
The above device operates as follows. From the analog-to-digital converter code pulses are applied via the synchronization unit to the inputs of the local temperature increments discriminator and to the add and subtract inputs of the reversible counter which responds by forming a parallel code of the actual temperature of the melt. Each time the temperature increment is .+-..epsilon..sub.o, at the respective output of the local temperature increments discriminator there is formed a pulse which is applied to the reset inputs of the time interval discriminator to whose count input there are fed synchronized clock pulses.
After each resetting, the time interval discriminator resumes time metering by counting synchronized clock pulses. After a certain time .tau..sub.o since the last resetting of the time interval discriminator at an output of the latter there is formed a pulse. This takes place only if no new pulse is fed to the reset inputs of the discriminator during the time .tau..sub.o. The pulse formation at the output of the time interval discriminator is indicative of a temperature arrest caused by crystallization of the melt, i.e. a temperature arrest when during a time equal to .tau..sub.o temperature increments do not exceed a predetermined value .epsilon..sub.o.
From the output of the time interval discriminator, the pulse is applied to the control input of the register, whereby the content of the reversible counter, which is the liquidus temperature code, is entered into the register and the flip-flop is set. Being fed with a signal from the set output of the flip-flop the digital display unit displays result of the analysis.
The above device is disadvantageous in that the reversible counter may malfunction during the analysis due to all kinds of interference. In such cases, the parallel code of the reversible counter may be considerably distorted. As a result, at the moment of detecting a temperature arrest, the register is fed with a parallel code substantially different from that of the liquidus temperature, and the digital display unit is fed false information on the carbon content in the melt.
In addition, the arrival of code pulses does not depend on the arrival of clock pulses and vice versa. As a result, in the time interval discriminator the synchronized clock pulses are counted even when the code pulses from the converter for converting the melt temperature signal to a numerical pulse code do not arrive for some reason, for example, because of a failure thereof. Such cessation of the arrival of code pulses may cause the same response of the device as in the case of a temperature arrest in the course of melt cooling. In this case, after a time period equal to .tau..sub.o since the cessation of the arrival of code pulses, the parallel code is entered into the register, which is not the code of the melt's liquidus temperature.
It is an object of this invention to provide, on the basis of simplest elements and units of digital computers, a digital device for determining the carbon counter in iron-carbon melts, which would improve the accuracy of the analysis by automatically correcting the parallel code at the output of the analog-to-digital converter in case of malfunctioning thereof, and by using a single source to generate code and clock pulses.
It is another object of the present invention to improve the reliability of such a device.
These and other objects of the invention are attained by providing a digital device for determining the carbon content in iron-carbon melts, comprising an analog-to-digital converter to whose input there is applied a signal carrying information on the actual temperature of the melt, electrically connected to a local temperature increments discriminator whose outputs are connected to reset inputs of a time interval discriminator having also a count input whereto synchronized clock pulses are applied, and an output electrically connected to a control input of a digital display unit to whose information input there is fed a parallel code of the carbon content in the melt, wherein, in accordance with the invention the analog-to-digital converter is a follow-up converter having a synchronized clock pulse output, two synchronized code pulse outputs and conversion suppression input; the electrical connection between the analog-to-digital converter and the local temperature increments discriminator being effected connecting the synchronized code pulse outputs of the follow-up analog-to-digital converter to inputs of the local temperature increments discriminator, the synchronized clock pulse output of the converter being connected to the count input of the time interval discriminator, the conversion suppression input of the converter being connected to an output of the time interval discriminator, a parallel code output of the converter being connected to an information input of a digital display unit.
Such a device improves the accuracy of the analysis.